Ultrasonic Misting Nozzle and System

This application claims the priority benefit of U.S. Provisional Patent Application Ser. No. 63/573,215 filed Apr. 2, 2024, the entirety of which is hereby incorporated herein by reference for all purposes.

The present invention relates generally to the field of misting to humidify/hydrate perishables, and more particularly to such misting using ultrasonic nozzles.

A variety of systems and methods are used to humidify/hydrate perishables in supermarkets and grocery stores, for example in meat, seafood, and produce display cases. Traditional systems and methods include using a water hose with a nozzle, or a spray bottle, to hand spray the perishables. Other systems and methods include mounting a number of nozzles connected to delivery pipes, with water under pressure supplied to the nozzles located at/in the display cases, resulting in a fine mist of about 100-micron droplets. These mounted-nozzle systems are commonly known as misting systems. Some misting systems include nozzles with air and water both under pressure, to create a very fine fog mist of about 6-micron to about 15-micron droplets. Some other fog-misting systems include centralized ultrasonic nebulizers that are similar to home cold humidifiers, with a water reservoir and an ultrasonic transducer located within the water reservoir. In these ultrasonic fog misting systems, the transducer operates at high frequencies to generate a fog mist that emanates upward from the top of the water level and is transported by piping to the delivery pipes, which includes holes (nozzles) to deliver the fog mist to the cases. And some other fog misting systems include vibratory mesh ultrasonic

There are several drawbacks to these ultrasonic fog misting systems, for example, safety, cost/time, coverage area, space, and water usage. As for safety, these ultrasonic fog misting systems include a reservoir of standing water, as well as standing water in the delivery pipes. These are potential breeding grounds for bacteria that when inhaled can cause serious health issues. This includes thebacteria, which causes Legionnaires' disease, with many people around the world having died from inhaling 2-3 micron size fog-mist droplets containing this bacteria (see, e.g., articles: https://www.cdc.gov/legionella/about/index.html and https://www.cdc.gov/legion ella/about/causes-transmission.html). It's possible to prevent/limit the growth of theand other bacteria. For example, some ultrasonic fog-misting systems include a mechanism that drains the open reservoir a few times a day, and others include an elaborate reverse-osmosis water-filtering system. But these preventive systems are mechanical, so they can (and do) fail, which is why some European countries have banned these types of systems. Also, these preventive systems require significant maintenance time and cost, and they waste a lot of water and energy.

As for cost/time, the equipment and its installation are very costly; depending on the system, this could run to $15,000 or even much higher. Also, the maintenance is very costly and needs to be performed by highly trained technicians; this maintenance could be around $5,000 per year. For many such systems, the main reservoir/transducer unit cannot be maintained on site and must be sent to the manufacturer's facility for yearly maintenance or replacement of the ultrasonic transducer, which involves significant added costs for shipping and labor, as well as the opportunity cost of a lengthy downtime.

As for coverage area, the fog mist of these ultrasonic systems (FMUS) moves in a very slow cascading flow, so the fog mist has a smaller target coverage area. Also, because of this slow cascading flow, any air movement in or near the case can disrupt the flow of the fog mist to the target area intended to be humidified. Further, for vertical display cases, the fog simply cannot reach the lower shelves of the cases.

As for space, the equipment of these ultrasonic systems takes up a lot of space and has a fairly large footprint. This can be an issue in many stores with limited floorspace.

And as for water usage, these ultrasonic systems use large amounts of water. Published water consumption specifications for these systems do not always include the water that must be dumped to refresh the reservoir, so actual water usage is typically higher than indicated in the specifications.

Accordingly, it can be seen that needs exist for improved misting systems. It is to the provision of solutions to this and other problems that the present invention is primarily directed.

Generally described, the present invention relates to devices, systems, and methods of generating a mist of liquid droplets and directing it toward a target area for humidification. The mist is generated by an ultrasonic misting nozzle device including an ultrasonic transducer, a control unit, and a housing. The control unit operates to control the ultrasonic transducer. The housing includes a liquid inlet, a drain outlet, a mist opening, and a collection chamber. The liquid inlet is connected to the collection chamber bottom periphery, the drain outlet connects to the collection chamber top, and the collection chamber bottom is adjacent and above the ultrasonic transducer, which is adjacent and above the mist opening.

In operation, a liquid (e.g., water) flows under pressure from the liquid inlet line discharge and into the collection chamber bottom. The ultrasonic transducer operates to induce a gas (e.g., air) to flow upward into the mist opening, through the ultrasonic transducer, and into the collection chamber. Also, the ultrasonic transducer generates gas (e.g., air) bubbles in the collection chamber bottom and generates and emits the mist (e.g., fog) downward out of the collection chamber through the ultrasonic transducer and the mist opening. The liquid (e.g., water) flows under pressure across and atop the ultrasonic transducer to displace the gas (e.g., air) bubbles from atop the ultrasonic transducer and mix with the gas bubbles to form a gas-infused liquid (e.g., aerated water) that flows upward within the collection chamber, away from the ultrasonic transducer, towards the drain outlet, and out of the collection chamber through the drain outlet.

In example embodiments, the collection chamber is tapered with a larger bottom than top, and the liquid inlet has a smaller cross-sectional area than the drain outlet. Systems of the misting devices include low-voltage electric power wiring to each of the control units, a feed line connected to the liquid inlets under positive pressure, and/or common supply and drain lines for all the misting devices.

These and other aspects, features, and advantages of the invention will be understood with reference to the drawing figures and detailed description herein, and will be realized by means of the various elements and combinations particularly pointed out in the appended claims. It is to be understood that both the foregoing general description and the following brief description of the drawings and detailed description of example embodiments are explanatory of example embodiments of the invention, and are not restrictive of the invention, as claimed.

Generally described, the present invention relates to ultrasonic misting devices and systems for delivering fine droplets of liquid to perishables. The misting devices and systems are described herein primarily with reference to generating and delivering a mist of water droplets to provide humidification (including hydration) to perishables (e.g., meat, seafood, produce, cheese, deli products, and/or flowers, etc.) in storage areas (e.g., supermarket display cases for purchase, storage rooms in supermarkets or warehouses, intermodal containers for transport, etc.). It will be understood that the misting devices and systems can be used as described herein, and/or adapted for use as known by persons of ordinary skill in the field, for use in delivering water, a disinfectant, another liquid, and/or a combination thereof, to provide humidification, disinfection, and/or other misting, to perishables, living beings (including humans), and/or other targets, in display, storage, passenger, and/or other target areas, in the same or other applications. Such other applications can include for example aviation (e.g., aircraft passenger cabins), cruise ships (e.g., all occupied spaces), trains and buses, retail stores, HVAC systems (equipment and/or ductwork), healthcare (e.g., waiting rooms, operating rooms, and/or patient rooms), pharmaceuticals, manufacturing (e.g., rooms where electronic devices are manufactured), and/or agriculture (e.g., poultry egg production facilities). Accordingly, various embodiments of the ultrasonic misting devices and systems use water and/or another liquid (e.g., a disinfectant and/or hypochlorous acid), in combination with air or another gas (e.g., ozone, for disinfection and odor control), to provide the described misting functionality (as such, water and liquid are sometimes used interchangeably herein, and air and gas are sometimes used interchangeably herein). An example of hypochlorous acid currently sold under the brand name PRODUCE MAXX by Chemstar (Lithia Springs, GA), used with their SAFEMIST brand system, an add-on option to misting systems.

Turning now to the drawings,show an ultrasonic misting nozzle deviceaccording to an example embodiment of the invention. The misting deviceincludes an ultrasonic transducer, a control unit, and a housing. These components can be made of conventional materials using conventional fabrication techniques and equipment, as is known in the field.

The ultrasonic transducerin typical embodiments is a vibrating-mesh ultrasonic transducer. Such vibrating-mesh ultrasonic transducersinclude a perforated sheet of metal or other material positioned within a peripheral piezoelectric element with an electrical connection. The electrical connectionis electrically connected to the control unitso that the ultrasonic transduceris powered and controlled by the control unit. In the depicted embodiment, the perforated sheet is circular and the peripheral piezoelectric element is annular (peripherally surrounding the perforated sheet), with the vibrating-mesh ultrasonic transducerthus being disc-shaped (and thus sometimes referred to as a metal mesh disc). Such vibrating-mesh ultrasonic transducersatomize the liquidto generate a fine mist cloud of water droplets, with each droplet having a diameter of for example about 2 microns to about 15 microns, about 2 microns to about 6 microns, or typically about 3 microns to about 5 microns (e.g., with a vibrating frequency of about 108 KHz to about 113 KHz). Vibrating-mesh ultrasonic transducersof this type are conventional and commercially available for example from TEKCELEO (Mougins, France).

In other embodiments, the ultrasonic transduceris other than a vibrating-mesh type, for example an immersion or contact ultrasonic transducer, another type of piezoelectric or capacitive ultrasonic transducer, or another type of transmitter (or transceiver) ultrasonic transducer, provided that it includes perforations configured to permit the airand mistto flow through it to provide the pass-through functionality described herein (e.g., this expressly excludes horn-type ultrasonic transducers). And in other embodiments, the ultrasonic transduceris other than disc-shaped, for example it can have a rectangular, polygonal, or other regular or irregular shape.

The control unitin typical embodiments is a printed circuit board (PCB) with an electrical connection. The PCB provides controls, including power on/off and typically a timer for on/off intervals. The PCB can be of a conventional type that is commercially available from numerous suppliers. In other embodiments, other types of conventional or future-developed control components can be provided. The electrical connectioncan be connected to by wiring (e.g., to a 5 vDC power supply) to power the control unitand thus the ultrasonic transducer. In other embodiments, the control unit is not local/individual to the ultrasonic transducerand part of the device, and instead a centralized control unit is located remote from the devicefor group control of a system of the devices.

The housingincludes a liquid inlet line, liquid drain line, and a bottom opening, with a collection chamberin fluid communication with all three of these, with the ultrasonic transducerpositioned below the collection chamberand above the bottom opening. Also, an on/off power switch can be provided on the housingand wired to the control unitso that each misting device(e.g., in a system including a plurality of them) can be independently manually turned on and off. The housingcan include multiple body components that collectively define the water inlet line, the liquid drain line, the bottom opening, and the collection chamber. For example, the housingcan include a main bodythat defines the water inlet lineand the liquid drain line, a cover panelthat connects to the main bodyto enclose the control unitwithin the main body, and a bottom panelthat connects to the main bodyand defines the bottom opening.

The bottom panelincludes the bottom openingin alignment with the ultrasonic transducerto expose the perforated sheet of the ultrasonic transducerand thereby allow air (or another gas)to enter through the bottom openingand thus the ultrasonic transducer. As such, the bottom panelcan be a clamp ring (e.g., as depicted) that connects to the main body, sandwiching the ultrasonic transducerbetween them to secure it in place and create a seal, as depicted. Alternatively, the bottom panel can simply be fasteners (e.g., clamps, clips, screws, etc.) that connect the ultrasonic transducerto the main bodyto provide the described functionality, with more of the ultrasonic transducerexposed, and with the bottom opening formed by the void space centrally located between the fasteners. In any event, the bottom openingtypically has a size (e.g., diameter or other transverse dimension) that is larger than that of the perforated sheet of the ultrasonic transducer, a shape (e.g., circular) that conforms to that of the perforated sheet of the ultrasonic transducer, or both.

In other embodiments of the housing, the liquid inlet line and the liquid drain line can be provided by tubing connected to a hollow body forming the collection chamber (with these separate components all enclosed within the housing), and/or the bottom opening can be defined by the portion of the housing adjacent the bottom of the ultrasonic transducer. It will be understood that these components can be provided in other arrangements to provide the same functionality described herein. Also, the housingcan be made of plastic or another suitable material.

The liquid inlet lineincludes a liquid intake(e.g., a tubing connector) at its intake end and a liquid dischargeat its discharge end. The liquid dischargeis positioned at a peripherally outer (side) and lower portion of the collection chamber. With the ultrasonic transducerpositioned below the collection chamber, the liquid dischargethereby delivers water (and/or another liquid)to a peripherally outer and upper portion of the ultrasonic transducer(see). The liquidis delivered into the liquid line intakeunder positive pressure, as discussed below.

In addition, the liquid inlet linetypically includes a flow constriction, with the liquid inlet line having a first segmentbetween the liquid intakeand the flow constrictionthat has a larger cross-sectional area than a second segmentbetween the flow constrictionand the collection chamber. The flow constrictionof each misting devicethrottles the liquidso the ultrasonic transducerof each misting devicereceives the same volume of liquid (this also increases the flow rate/speed of the liquidflowing onto the ultrasonic transducer). The flow constrictionis particularly advantageous when the misting nozzle deviceis used in a system of multiple serially connected nozzle devices, to allow the last nozzle devicein line to get close to the same volume of liquid as the first nozzle device in line (as such, the flow constriction may be excluded in systems with one or few nozzle devices).

In other embodiments, the flow constriction is positioned at the liquid intake (e.g., included in a tubing connector, so the entire liquid inlet line has the same cross-sectional area and is smaller than a connected liquid line), is positioned upstream of the housing as a separate component, or is not included (with the pressure and flow rate set and/or controlled by other devices).

The liquid drain lineincludes a drain liquid outlet(e.g., a tubing connector) at its outlet end and a liquid intakeat its intake end. The liquid intakeis positioned at the top of the collection chamber(e.g., centered at an apex of a tapered collection chamber). In this way, the liquidthat is feed by the liquid inlet lineto the ultrasonic transducer, but that is not converted into the mistby the ultrasonic transducer, and that is infused with air bubbles by the ultrasonic transducer(i.e., air bubbles emitted from the top side of the vibrating mesh ultrasonic transducer) to form an aerated liquid/, is directed into the drain line intakeunder the force of the liquid pressure from the liquid inlet line.

The bottom openingis positioned at the bottom of the housingso that the mistgenerated by ultrasonic transducerflows downward under the force of gravity. The bottom openingprovides fluid communication between the collection chamber(above it) and the ambient target area (below it, targeted for humidification, etc.). The perforations of the ultrasonic transducerare selected to be sufficiently fine/small, and the pressure of the liquiddelivered to the ultrasonic transduceris selected to be sufficiently low, that the pressurized liquiddoes not pass downward through the ultrasonic transducerand out of the bottom opening. At the same time, the perforations of the ultrasonic transducerare selected to be sufficiently large that air (and/or other gasses)can pass upward through the ultrasonic transducerand into the collection chamberduring operational use (high-frequency oscillations) of the ultrasonic transducerto generate the fine mist of liquid droplets, and those fine-mist liquid droplets can then pass downward through the ultrasonic transducerand out of the bottom openingtoward the target area. For example, the sufficiently low pressure of the liquiddelivered to the ultrasonic transducer(into the collection chamberat the liquid discharge) can be about 0.5 psi to about 5.0 psi (e.g., about 1.5 psi to about 3.0 psi, typically about or below 2.0 psi). A pressure regulator (e.g., as described below) can be integrated into or connected to the nozzle deviceto provide this sufficiently low liquid pressure at the liquid discharge, if the liquid pressure at the liquid intakeis higher than needed to provide the described functionality.

It should be noted that the embodiments disclosed herein are described in an orientation with the mistemitted downward through the bottom openingand with the air-bubble-infused liquid/rising upwards from the ultrasonic transducerthrough the collection chamber, as this orientation provides excellent results. It will be understood that this orientation is done for convenience in describing these embodiments, and references to bottom, top, etc. are thus for convenience and not limiting/required of the invention. Thus, these and other embodiments can be installed in other orientations, with modifications as may be needed, and used to provide the same functionality described herein, for example with the mistemitted laterally or angularly.

In the depicted embodiment, the collection chamberhas bottom and top cross-sectional areas (e.g., parallel to the plane of the ultrasonic transducer), with the bottom areabeing larger than the top area, and with a peripheral sidewallthat extends between the bottom and top areasandand that is tapered inwardly and upwardly. The larger bottom areais adjacent and in fluid communication with the ultrasonic transducer, with the liquid inlet line dischargelocated at and in fluid communication with a peripheral portion of the larger bottom area. And the smaller top areais in fluid communication with the drain intake, with the top arealocated where the drain intakemeets the collection chamber). Also, the drain intakeis located at or adjacent the apex of the tapered collection chamber. In typical embodiments, the drain intakeand top areaare circular, and the ultrasonic transducerand bottom areaare circular, with the drain intakecentered and coaxial relative to the collection chamberand the ultrasonic transducer. The tapered collection chamberis thus configured to provide a space where the air bubbles (generated atop and by the ultrasonic transducer) can mix with the remaining liquid (not converted into mist) and thereby be carried away (induced/influenced to flow, under the positive pressure of the liquid) from atop the ultrasonic transducerand toward the drain intakeso the air bubbles do not sit atop and clog the ultrasonic transducer(the circular arrows within the collection chamberinindicate mixing of liquidand air bubblesinto aerated liquid/, and not necessarily the actual flow paths).

The sidewallcan be provided by a single continuous wall or multiple wall segments, and can define the collection chamberwith a shape that is conical (including frustoconical, as depicted) and thus linear in cross section, dome-shaped and thus curved in cross section, stepped and thus rectilinear in cross section, pyramidal (e.g., with a triangular or rectangular bottom areaand transducer) and thus linear in cross section, or of another configuration (including polygonal and other regular and irregular shapes) that provides the described functionality. The depicted conical shape of the chamberhelps funnel the aerated liquid upward within the collection chamber and away from the ultrasonic transducer. As noted, the tapered collection chamberfunctions to collect the remaining liquidand the generated air bubbles, mix them into the drain liquid (e.g., aerated water and/or other liquid)/, and direct/guide and carry it upward and away from the ultrasonic transducerunder the pressure of the flowing liquidinto the drain intake. In this way, the drain liquid/does not accumulate and pool on top of the ultrasonic transducer, which pooling would interfere with transducer operation to generate the fine mist of droplets.

In other embodiments, the collection chamber has other configurations. For example, the collection chamber can be cylindrical or have another regular or irregular non-tapered shape that provides a space for the air bubbles (created and infused into the drain liquid by the ultrasonic transducer) to move away from the ultrasonic transducer to avoid pooling and thereby “clogging” or “jamming” the ultrasonic transducer in a way that impairs its performance. In some such other embodiments, the collection chamber includes one or more sharp-tipped spikes (e.g., extending downward from an upper surface portion and into a middle portion of the chamber) that burst the air bubbles. In other such embodiments, the misting device (e.g., the liquid inlet line) includes smoother turns to help keep bubbles from congregating. And in these and./or other embodiments, a control can be provided (e.g., included in the control unit) that regularly cycles the ultrasonic transducer off for a brief time period (e.g., 5-10 seconds) to allow the air bubbles to dissipate and then back on to resume misting operation.

In addition, in typical embodiments, the liquid line discharge(and the liquid inlet segment) has a smaller cross-sectional area than the drain line intake(and the drain line). In this way, there is a higher fluid flowrate at the liquid line discharge(into the collection chamber) than at the drain line intake(out of the collection chamber). The liquidentering the collection chamberat a higher flowrate than the flowrate of the aerated liquid/exiting the collection chambercauses the liquid to displace the air bubbles from atop the ultrasonic transducer. This helps induce the aerated drain liquid/(that does not pass downward through the ultrasonic transducerand out the bottom openingas mist droplets) to flow upward through the collection chamberand out of the drain line, instead of pooling on top of the ultrasonic transducer.

Further, the liquid line dischargedelivers the liquidinto the collection chamberat the bottom periphery of the collection chamber, and the drain line intakereceives the drain liquid/at or adjacent the top (e.g., conical apex) of the collection chamber, as noted above. The periphery is the radially outward portion of the collection chamber bottom, as depicted. In use, the liquidis caused to flow through the liquid line dischargeinto the bottom areaof the collection chamber, by the positive liquid pressure, and across the ultrasonic transducerfrom its periphery radially inward towards its center. At the same time, airis caused to flow generally vertically upward from the bottom openingthrough the ultrasonic transducerand into the bottom areaof the collection chamber, by high-frequency (e.g., 108 kHz to 115 kHz) vibratory oscillating/pulsing operation of the ultrasonic transducer. The vibratory operation of the ultrasonic transducerthen causes interaction between the airand liquidin the bottom areaof the collection chamber(immediately on top of the ultrasonic transducer) to form the mist of fine liquid dropletsand the air-infused aerated drain liquid/(the water and/or other liquid that is not vaporized/atomized by the transducer). Then the fine mistis expelled downward through the ultrasonic transducerand out the bottom openingto the target area, while the aerated drain liquid/flows generally vertically upward away from the ultrasonic transducerto collect and flow through the top areaof the collection chamberand into the drain line intake. In this way, the peripheral bottom position of the liquid line dischargeand the top central position of the drain line intakehelp induce the aerated drain liquid to flow upward through the collection chamberand out of the drain line, instead of pooling on top of the ultrasonic transducer.

Some of the air bubblesin the collection chambermight be expelled back through the ultrasonic transducerand back out the bottom opening(e.g., in orientations with the mistemitted upwards or laterally), but this is not significant to functioning of the misting device. In any event, the result is the mist cloud of fine dropletsis projected downwards and outwards (e.g., aboutfeet to aboutfeet in typical embodiments), dispersing over the target (e.g., food products) and increasing the humidity of the target environment area.

In the depicted embodiment, the liquid inlet lineis substantially vertical (and thus substantially parallel to the drain lineat the drain line intake) and the liquid line dischargeis directed downward to deliver the liquiddownward into the periphery of the larger bottom areaof the collection chamber. In other embodiments, the liquid inlet line(least the portion adjacent the chamber bottom periphery forming the liquid discharge) is substantially horizontal (and thus substantially perpendicular to the drain lineat the drain line intakeand parallel to the vibrating mesh transducer) and the liquid line dischargeis directed radially inward to deliver the liquid laterally into the periphery of the larger bottom areaof the collection chamber. In some such embodiments, the liquid inlet line (least the portion adjacent the chamber bottom periphery forming the liquid discharge) is arranged tangentially to the chamber bottom or otherwise not aligned through the center of the chamber bottom in order to induce a whirlpool flow in the chamber. Other arrangements of the liquid line dischargecan be used to help induce the aerated drain to flow upward through the collection chamberand out of the drain line, instead of pooling on top of the ultrasonic transducer.

A number of the misting nozzle devicescan be combined into a misting system that delivers the generated mistto the target area. In some embodiments, the misting devicesare mounted in place directly (e.g., to a display case) and connected to directly (e.g., by liquid feed, liquid drain, and power lines). In other embodiments, the misting devicesare mounted in place and connected to indirectly, with one or more of the devicesincorporated into a misting module that is then directly mounted in place and directly connected to.

For example,shows a misting moduleincluding one of the misting devices. The misting modulecan be of the type disclosed by U.S. Pat. No. 11,493,215, issued Nov. 8, 2022, which is hereby incorporated herein by reference. In the depicted embodiment, the misting moduleis a modular adaptation of the fog-generation systemshown and described with reference toof the '215 Patent. As such, the depicted misting moduleincludes a fluid delivery barwith two fluid lumens (channels/headers)and, with each lumen connected in fluid communication with a respective manifoldand. The misting nozzle deviceis connected in fluid communication between the two manifoldsand(in place of the sprayer nozzleof the '215 Patent), with one of the lumens and manifolds feeding the liquid to the misting nozzle device(as in the '215 Patent), and with the other lumen and manifold draining the aerated liquid drain from the drain outlet(instead of feeding the air to the sprayerof the '215 Patent). Thus, in the depicted embodiment, air is drawn in through the ultrasonic transducer(instead of through the air lumenand manifoldof the '215 Patent), so instead of the lumens and manifolds both being feed/intake lines, one is a feed/intake and the other is a drain.

It will be understood that the misting devicecan be incorporated into other misting modules, including other adaptations of the embodiments disclosed by the '215 Patent as well as other embodiments.

Turning now to, there is shown a misting systemaccording to another embodiment, including a plurality of the misting devicesto provide the misting functionality described herein. In this embodiment, the misting devicesare incorporated into the herein-described misting modules, which are connected together end-to-end into an integrated and continuous track of the misting devices. The track of misting devicescan be installed for example in the canopy of a produce display case, or the upper interiors of meat and seafood display cases. The misting devicescan be provided in a number and spacing selected for the intended target area (e.g., display case).

The misting systemincludes electric power wiring to the misting devices. For example, electric power can be connected to the misting devicesby a wiring harness, including a single trunk electric power wireand an individual electric power wire running from the trunk lineto the electrical connectionof each misting device. Thus, even though there are a large number of the misting devices, and conventional design would dictate a single centralized control unit and a large number of individual control wires from the central control unit out to the misting devices, instead each misting devicehas its own control unitthat is fed by only a power wire, with the local/dedicated control unitseliminating the need for individual control wires out to each misting device.

Also, the electric power wiring can be connected to standard 120/240 v power supplied by the local electric utility, and a transformercan be connected in line to step down the power to the desired level (e.g., 5 vDC) for the control unit. The single trunk electric power wireand the individual service electric power wirescan thus be provided by conventional low-voltage electric wires.

The misting systemalso includes a water (and/or other liquid) feed lineand a drain line. The feed and drain linesandcan be provided by conventional tubing connected directly or indirectly to the liquid line intakeand the drain line outlet. A pressure regulatorand/or a drippercan be included in the feed lineto control the pressure and/or flowrate of the liquidfed to the misting devices. For example, in typical embodiments, the pressure regulatorcan operate to reduce the positive liquid pressure to an operating level between about 0.5 psi and about 5.0 psi (e.g., about 1.5 psi to about 3.0 psi, typically about or below 2.0 psi) and to maintain it there during use (city water systems often deliver tap water at 40 psi to 60 psi, and sometimes up to about 80 psi), to provide the functionality described herein. The dripperis typically positioned inline after the pressure regulator. The dripperfunctions to output a uniform liquid flow rate, regardless of the liquid pressure, as this helps ensure proper operation of the ultrasonic transducers. Depending on the size of the misting system, the drippercan be selected with a size/capacity of for example 1 gallons/hour (GPH), 2 GPH, or 5 GPH. These pressure-control and flow-control components can be of a conventional type known in the field, for example, the drippercan be a pressure-compensating dripper of the type used in agricultural irrigation systems. It will be understood that other components can be included to control the liquid pressure to provide the misting functionality and avoid the aerated liquid pooling on top of the ultrasonic transducers, as described above.

Also, the downstream end of the liquid feed lineis plugged, and the upstream end of the liquid drain lineis plugged, because these lines are not configured in a closed loop. In other embodiments, the liquid feed is supplied to both ends of the feed line and the drain line is open at both ends.

In addition, the liquid feed lineis connected to a liquid supply, typically a conventional water tab with the water supplied by a local water utility. Thus, the water supply is under positive pressure, which pushes the feed liquidthrough the feed lineto the misting devices, and pushes the aerated drain liquid/out of the misting devicesand through the drain line. So a liquid pump is not needed (as a component of the system) to provide positive liquid pressure (with the pump running forward) or to provide negative/vacuum liquid pressure (with the pump running in reverse), and a liquid reservoir is not needed as the liquid supply. Furthermore, typical local water supplies operate at positive water pressures of about 40 psi to about 60 psi., so the pressure regulatorand/or drippercan be selected to reduce the positive liquid pressure to the desired operating pressures of the systems.

Turning now to, there is shown an open-loop (non-circulatory) misting systemaccording to another embodiment, including a plurality of the misting devicesto provide the mistingand functionality described herein. This figure shows schematically the flow of the feed liquidand the aerated drain liquid/through the misting devicesin an open-loop configuration including a water (and/or other liquid) feed line with an upstream end connected to a positive-pressure source (e.g., pressurized city water or a pump) and a downstream end plugged, and with a drain line with an upstream open end and a downstream plugged end.

Turning now to, there is shown a closed-loop (recirculatory) misting systemaccording to another embodiment, including a plurality of the misting devicesto provide the mistingand functionality described herein. This figure shows schematically the flow of the feed liquidand the aerated drain liquid/through the misting devicesin a closed-loop configuration including a water (and/or other liquid) pumpand a drain tank. The liquid pumpprovide the positive liquid pressure (instead of pressurized city water) and the drain tankeliminates the air bubblesfrom the aerated drain liquid/.

Accordingly, the various embodiments provide various advantages over the prior art, for example the following. One area of advantage results in embodiments in which each individual nozzle has its own control board. This enables routing a single electric supply line to each nozzle, instead of having multiple control lines from a centralized controller to the nozzles. This also allows flexibility in having a variety of nozzles, because there is not a central controller. And this further allows including an individual electric switch on each devicefor individual nozzle turn off without effecting the performance of the other nozzles.

Another area of advantage results in embodiments having two (e.g., parallel) liquid lines, with one a supply line and with the other a drain line that discards the liquid not used by the nozzles as well as the air bubbles produced by the nozzles during the process of creating the misting fog. This eliminates the need for recirculation of water (or other liquids) through a centralized reservoir.

Another advantage is safety. At least some embodiments use water directly from the plumbing system, with or without a reverse osmosis water purification equipment or any other water filtration equipment. Additional disinfecting material can optionally be injected into the water, if desired. There is no need for a pressure pump or circulating pump. There is no need for a reservoir of any kind, especially the kind where the water is exposed to the atmosphere enabling bacteria to grow, for example the bacteria causing Legionnaires' disease. And there is no standing water in the delivery pipes.

Another advantage is low water and/or other liquid consumption. For at least some embodiments, a misting system including about 23 nozzles consumes about 1 gallon of water per hour.

Another advantage is simple and easy use. For at least some embodiments with individual power switches for each misting device, it is simple and easy to turn off individual nozzles.